Integrating a Solar PV System with Pumped Hydroelectric Storage at the Mutah University of Jordan

Abstract

This paper focuses on designing and assessing Pumped Hydroelectric Energy Storage Systems (PHESs) connected to the grid and a PV system for self-consumption constructed at Mutah University in an area of high solar potential. By focusing on the PHES and PV literature, data in the field were acquired based on the grid code needed in Jordan. Next, a search to find a suitable location for installation was conducted. Afterwards, a load profile was added to calculate the energy demand of the university. Then the productivity of the solar power plant of Mutah University was included. Finally, MATLAB software was used to realize the amount of energy to be stored; these data were used to implement the system that was chosen and dimensioned. A PHES layout was created to find the most accurate values for parameters to optimize system performance and to investigate loss analysis. The main finding is that the system attains 9230.89 MWh/year. An annual load yields 4430 MWh/year, which covers the Mutah University demand with an estimated saving of USD 287,607,993.

1. Introduction

One of the most important concepts in the twenty-first century is energy. With increased fossil fuel consumption and rising air pollution, there is a strong demand for efficient energy and a search for clean renewable energy resources that can replace fossil fuels to support the growth of our economy and society. A renewable energy system, which produces energy by converting natural phenomena into useful forms of energy, is one of the options. Solar radiation, wind turbines, hydropower, geothermal heat, and biomass energy are usually the most widely used renewable energy sources [1,2]. Solar energy, which is light radiation, and heat from the sun that has already been collected by humans using a variety of ever-evolving technology account for most of the available renewable energy on Earth. PV technologies are the method to harness solar energy to generate electricity, and they can range in size from small roofs or portable systems to large utility-scale producing plants. Geographically and climatically, Jordan offers some of the best wind and solar energy potential in the world. A major factor is the requirement to use more renewable energy sources. Jordan is regarded as an exceptional nation due to its abundant solar energy resources, which can satisfy the majority of the nation’s energy needs. Jordan is also a sunbelt state, meaning that much of its territory is subject to exceptionally strong solar radiation. Jordan is located between latitudes 32° North and 36° East [3,4]. Jordan experiences 3125 h of sunshine annually, or nearly 300 bright days, with an average daily solar radiation of between 5 and 6.5 kWh/m² [1,3,4]. The first private sector solar PV project, which was conducted in 2013, was the Applied Science Private University (ASU) project, which has a capacity of 250 kW and fulfills 25% of the university’s energy requirements. In addition, with a 5.17 MW capacity, the Al Azraq solar energy complex was finished in 2015. Future private and public sector solar PV plant development plans have been made for the 200 MW and 100 MW Almafraq and Al-Quweira solar PV plants, respectively [5]. At Ma’an, Aqaba, and Almafrak, further projects with a combined capacity of 400 MW have also been assigned. The first solar project developed by the government was the 52.5 MW Shams Ma’an Solar PV power station. In line with the world record price of 0.0589 USD/kWh, the Shams Ma’an Solar PV power facility reportedly offered an unusually low tariff of 0.06 USD/kWh [6]. Jordan has created an environment that encourages investment in renewable energy, primarily solar and wind energy, allowing public and private institutions, as well as homes, industry, and commerce, to rely on renewable energy systems for their consumption purposes and lower their electricity bills. These advances follow a national strategy targeted at increasing the amount of renewable energy to 10–11 percent by 2021, equating to 1.600 MW of renewable generating capacity. The plan was recently modified, reflecting the government’s progress in developing many of its sections. For example, initial plans planned for 600 MW of solar energy, which was installed by 2020, but significant advances in solar technology have prompted local governments to raise this goal to 1000 MW [7]. The solar energy sector in Jordan will keep growing. As a result, if the electricity distribution company fails to employ an effective energy storage system, there will be an imbalance between the energy produced by PV solar plants and the amount of energy demand. A promising alternative approach to load balancing and energy storage is the use of PHES systems. By releasing energy during times of high demand and using it to raise water to high-potential energy reservoirs during times of low demand, they can also profit from daily variations in the price of energy. A number of energy storage methods already exist, some of which have been around for centuries. The purpose is to make them stable, dependable, and cost-effective while applying the best technology to each energy source or location [8]. The many technologies available for energy storage are frequently classified according to the purpose of the energy storage, with the most popular being the form of energy storage and the period of release. PHES stations for storing energy are one of the most important and well-known effective solutions for storing electrical energy. This type of station is similar in design to electrical resistive stations on dams but differs in its mechanism and objective operation [9]. Electricity consumption may rise at specific times of each day or every year (based on the weather or operating air conditioners and electric heaters). When electricity consumption exceeds the amount of production, electricity companies are forced to increase their output to satisfy customer demands and compensate for any lack. Therefore, using stored electrical energy when needed would be a great advantage. On either hand, electricity consumption may reduce throughout a single day, or the generation of electric energy may be larger than the demand at a specific point in time. Energy sources with difficult-to-control resources are usually the source of this excess output. This is why electric providers try to store energy that is in excess of the demands of consumers so that it can be used when there is a need for electricity rises [10]. Future energy in Jordan will mostly depend on storage systems for non-distributable renewable electricity generation. Moreover, rapid management of electricity flow to power grids will be necessary due to the rapid proliferation of renewable energy systems [11]. Morocco has one PHES plant in operation, which is the only scheme in the Middle East and North Africa (MENA) region, with a capacity of around 463 MW (“Afourer” plant) [12]. There is a pre-feasibility study for a 1000 MW pumped storage plant in Saudi Arabia that could obtain power for 8 hrs at peak load to decrease the need for a 1000 MW thermal plant burning heavy fuel oil [13]. Jordanian researchers have started to become interested in energy storage studies. They have designed and analyzed a hybrid system (wind and pump storage) at King Talal dam. After technical and economic analysis took place assuming daily operation for 2–3 h at peak load but water collected for 30 h, the total annual energy production was calculated to be 26.66 GWh from a 10 MW wind farm and a 5.2 MW pumping storage system [14]. Researchers reported that six out of ten dams in Jordan have the opportunity to have PHES plants by utilizing existing dams as lower reservoirs and provide candidate locations for upper reservoirs [15]. The main premise of this paper is that it is feasible to build a PHES system in Jordan that uses water pumping to a high-elevation reservoir to reduce waste energy produced by solar panels during off-peak demand. On the other hand, this high-potential-energy water will be provided to hydropower turbines during periods of peak demand to meet the demand for electricity on the grid. Jordan also possesses several solar energy systems in its north and south regions.

2. Methodology

2.1. Location Survey

In general, a PHES system is made up of two reservoirs separated by a large elevation difference. High-elevation regions, such as hills or mountains, should be considered for PHES construction. The lower reservoir is close to the power plant at the lower end of the hill, while the upper reservoir is at the top. At the top and bottom of the hill, there should be enough room for water storage.

2.2. Energy Storage Capacity

Determining the quantity of energy that the PHES system can store was the target of our study. The procedures listed below can be used to estimate the pump power of water required to determine the quantity of electrical energy that can be converted into potential energy in high-elevation storage [16]:

• Estimate the rated pumping head.

• Determine the rated pump power of water in the higher reservoir when a pump with 1 MW rated power is employed to raise the water level to the rated head.

(1)$\mathrm{PP}= \mathrm{QP}\times \mathsf{\eta }\mathrm{P} \mathrm{g}\times \mathsf{\rho }\times \mathrm{h}$

where:

$\mathrm{QP}$: Rated volume flow rate (m³/s).

$\mathrm{PP}$: Rated pump power (W).

$\mathsf{\eta }\mathrm{P}$: Pump efficiency.

$\mathrm{g}$: Acceleration of gravity (9.8 m/s²).

$\mathsf{\rho }$: Density of water (1000 kg/m³).

$\mathrm{h}:$ Head (m).

• 3.. Identify the number of hours a pump can run continuously at a given rated power in each period.

• 4.. Estimate the volume of the upper reservoir that is needed.

(2)$\mathrm{VR}=\mathrm{QP}\times \mathrm{T}$

where:

VR: The upper reservoir’s volume (m³).

T: Pumping time (s).

The system capacity can now be extended by multiplying the necessary rated pumping power by the volume of the top storage, which was previously only used to store energy for 1 MW rated pumping power.

2.3. Required Site in Jordan

It is essential to remember that meeting the required site’s geographical specifications is not simple. Therefore, to lower the total cost of capital infrastructure for the project, it is necessary to investigate and discover the best places to meet the highest number of PHES installation requirements.

2.3.1. Mutah University

Mutah University is located in southern Jordan, where a solar energy project provides energy to the university. The PV solar project at Mutah University is shown in Figure 1. The University of Mutah has several colleges and sites outside its main campus, so the university was forced to link the solar power plant and operate it with the Wheeling system in agreement with the Electricity Distribution Company. The maximum load of the University of Mutah is 6.4 MW. The solar power plant is designed with a nominal capacity of 5 MW, and the actual capacity of the station is 4.4 MW. The Electricity Distribution Company collects JOD 0.007 for every kilowatt produced, and there is a transit cost allowance of 6% as an allowance for electrical loss. Thus, the actual capacity of the solar energy project at the University of Mutah is 4.4 MW_P.

Since the annual daily average of solar radiation received at a tilt angle of 22° is 6.27 kWh/m², the location has a significant solar energy potential.

2.3.2. Candidate Reservoir Locations

Possible candidate reservoir locations are near the electric grid. This is beneficial in terms of the cost of construction (i.e., reducing electrical transmission expenses). According to Figure 2, the height between the top and lower storage is approximately 85 m. Upper storage is at an elevation of 1130 m above sea level, while the powerhouse is at a height of 1045 m, whereas the area of the lower reservoir that is available is 220,000 m² with dimensions of length 550 m and width 400 m.

A comprehensive evaluation of the water balance for the inflow volume, outflow volume, and storage volume is required to determine the stored electrical energy in the planned PHES system at Mutah University and to guarantee that the water level is available throughout the storage process. The methodology described in Section 2.2 can be used to calculate the amount of water needed to operate the PHES system in the potential locations. The rated discharge from the pump at the rated head is calculated to be 1.079 m³/s using Equation (1) and the rated pumping head at the proposed site has a height difference of 85 m. Using Equation (2) and the assumption that the pump will run continuously for 12 h, upper storage of 46.627 × 10³ m³ volume is needed. The upper storage, which was previously used to store water for only 12 h at 1 MW rated pumping power, may now easily be expanded to increase the system capacity by multiplying the required rated power pump by the volume of storage. If a PV solar system with a 5 MW capacity is employed, 233.135 × 10³ m³ of upper reservoir space will be needed to store energy for 12 h.

2.4. Design of PHES

Grid-scale energy storage technologies such as PHES systems can aid in the growth of the nation’s energy sector. They give grid stability, which ensures that electric supply reliably meets electrical demand in real time. The biggest challenge in ensuring reliability is that the power source has no shelf life; it must be generated when required, and electricity demand is changing all the time. Electric energy is converted into hydraulic potential energy in PHES systems, which can be stored until needed and then converted back into electricity. This supports the electrical grid by assisting the balance of power flow across the distribution network by storing extra energy when the demand of electricity is low and supplying it at high demand. These systems combine a hydropower generating set, a turbine, a generator, and an electric pump. The system may operate in one of two modes: where water is pumped into the higher reservoir in the pumping mode; and in the generating mode, where water is released into the lower reservoir and passes through turbines attached to the electric generators [17].

2.4.1. The Selection of Turbine

In the initial stages of the design, a few fundamental machine requirements should be addressed. For a hydraulic turbine, the requirements are, namely, head H, volumetric flow rate Q, and rotational speed N [18]. Figure 3 illustrates the relationship between the primary hydraulic turbines’ total head H (m), flow rate Q (m³/s), and power capacity P (MW). In this research, P = 1 MW, Q = 1.07 m³/s, and rated head H = 85 m were used to calculate each set’s capacity. It can be seen from Figure 3 that Francis turbines will perform well, but this is insufficient to make a choice.

The specific speed Ns is a non-dimensional parameter that is typically used to select the most suitable machinery. The Ns value provides a suitable machine that will meet the specified typical demand of high efficiency. Equation (3) can be used to calculate it [20]:

(3)$\mathrm{Ns}= \mathrm{N}\times { \mathrm{p}}^{0.5}/{\mathrm{H}}^{1.25}$

where N is the runner’s speed in RPM, P is the power output in hp, and H is the head’s height in feet.

Calculations are now possible for Ns by substituting N, P, and H into Equation (4):

(4)$\mathrm{Ns}=\mathrm{N}\times {\mathrm{p}}^{0.5}/{\mathrm{H}}^{1.25}=1000\times {1341.02}^{0.5}/{278.87}^{1.25}=32.13$

According to [18], the specific speed ranges over many models of hydraulic turbines. As a result, the Francis turbine will be the ideal turbine for this work.

2.4.2. Determination of the PHES Site in Jordan

There is a valley in the location that has all the properties described, and it is near the Mutah solar project, so it can be used in the PHES system design process. As a result, it is the ideal potential location for use as a case study in this research to design a PHES system. A topographical map for the suggested storage system region, which contains the system components upper reservoir, powerhouse, and lower reservoir, is shown in Figure 2.

2.5. Specifications of the Storage System’s Components

The upper reservoir, lower reservoir, powerhouse, and conduit are the four components of the storage system. They are described in the following sections.

2.5.1. Upper Reservoir

This is a water pool at the top of a hill that creates a suitable height of water to flow into the lower water reserve. The proposed upper reservoir will be located on the top hill, as seen in Figure 2. The hill’s crest is 1130 m above sea level, with a storage contour at 1045 m. The area of the upper reservoir that is available is 240 × 10³ m² with dimensions of 600 m length and 400 m width.

2.5.2. Lower Reservoir

This is a water pool for storing a volume of water in a low area compared to the high-water reservoir and nearest to directly beneath it. The selected lower reservoir is located near the university at a height of 1045 m above sea level.

2.5.3. Powerhouse

The power plant would be at the lower reservoir, near the end of the water channel. In pumping mode, the power needed to pump the rated discharge into the higher reservoir is calculated as follows:

(5)$\mathrm{PP} = \mathsf{\rho }\times \mathrm{g}\times \mathrm{h}\times \mathrm{QP}/\mathsf{\eta }\mathrm{P}$

where:

$\mathrm{PP}$: Rated pump power (W).

$\mathrm{QP}$: Rated volume flow rate (m³/s).

$\mathsf{\eta }\mathrm{P}$: Pump efficiency.

$\mathrm{g}$: Acceleration of gravity (9.8 m/s²).

$\mathsf{\rho }$: Density of water (1000 kg/m³).

The suitable region for the upper storage, as mentioned earlier, has a contour at 1130 m above sea level, resulting in a minimum head of 1045 m and a rated head of 85 m. The top reservoir’s effective storage capacity, which can be used to produce energy, is thus decreased (233.130 × 10³ m³). It is suggested to add five reversible pump–turbine sets; each has a rated capacity of 1 MW. Equation (1) can be used to determine the rated discharge from each turbine at the rated head, rated power output, and 0.9 generator efficiency. This value is 6.66 m³/s. It is predicted that the lower reservoir’s water level will always be maintained at 1045 m above sea level. The amount of water that can be pumped into the higher reservoir from the lower reservoir is 1.079 m³/s using a pump that has a rated capacity of 1 MW, an average head of 85 m, and a pump efficiency of 0.9. The properties of the suggested PHES system are shown in Table 1.

2.5.4. Conduit

This consists of several pipes that are joined to each other and connect the higher reservoir to the lower reservoir. An 85 m long water conduit uses a pump turbine to link the lower reservoir to the upper reservoir. As a result, the L: H ratio is computed to be 1.081 (1130/1045), which is within the allowable design range. A variety of fittings would be necessary (e.g., elbow fittings, pipe entrance fittings, and container exit fittings), which may raise friction losses in the piping system.

2.6. Piping Design

Maintaining fluid velocities of around 7 m/s through all piping connection joints is required. This is advised for a variety of reasons [21] (friction loss, vibration and noise, erosion/corrosion, hydraulic shock, and extremely high velocity). As previously noted, calculating the right diameter for the piping system is critical to keep the volume flow rate within the acceptable range [22]. The designed velocity for pumping mode is 5.8 m/s, and the rated flow rate Q is 1.079 m³/s. The diameter of the piping system is 0.18 m. The volume flow rate in the generating mode is higher than in the pumping mode, even though both have the same diameter of 0.18 m. As a result, the velocity is 7.3 m/s, which is within the allowed limit.

3. Power System Modelling

3.1. Power System Characteristics

The proposed configuration is represented in Figure 4.

3.1.1. PV Solar Power Plant at Mutah University

The PV solar system consists of solar photovoltaic modules (14,738) and monocrystalline modules (type JA solar). The characteristics of the modules are shown in Table 2.

The solar inverter is one of the most critical parts of a solar PV system. It changes PV direct current (DC) into alternating current (AC). The characteristics of the inverter utilized in the Mutah University project (a type of SMA solar inverter) are given in Table 3.

Two 1500 kVA and two 1000 kVA transformers are used to step up the 0.48 kV voltage to medium voltage to connect the PV power plant to the grid. In this work, the power system will simulate the addition of 5 MW of solar power and electrical load in 2020/2021 for the university, as well as the addition of a PHES. As a reference percentage for the rating component, actual hourly solar energy productivity data obtained from Mutah University solar energy will be used. Figure 5 shows daily figures for Mutah University’s solar PV system, which has a total capacity of 5 MW.

3.1.2. Defining a PHES

The amount of energy to be stored will be determined by monitoring the load flow between electrical loads and solar energy output. The amount of energy stored in a PHES depends upon the behavior of PV generation and demand energy [23] where the power generated (P_Gen) must meet the power demand load (P_Dem); these are shown in Equations (6) and (7), respectively:

(6)$P_{Gen}\left(t\right)=P_{PV}\left(t\right)$

(7)$P_{Dem}\left(t\right)=P_{Gen}\left(t\right) \pm P_{PHES}\left(t\right)$

where P_PV(t) and P_PHES(t) are the power produced by a PV and PHES, respectively. It should be noted that:

• -. If P_Dem(t) > P_Gen(t), the extra power from the hydro-turbine P_PHES(t) > 0, and makes up the shortfall in the power generated from P_PV(t).

• -. If P_Dem(t) = P_Gen(t), P_PHES(t) = 0; the power generated by P_PV(t) is just sufficient to supply the demand.

• -. If P_Dem(t) < P_Gen(t), P_PHES(t) < 0; the excess power generated is stored by the PHES.

3.1.3. Defining the Electrical Load Data

All of Mutah University’s energy loads will be included in the simulated power system. The characteristics of the load profile are obtained from the Electrical Distribution Company (EDCO), taken from actual hourly load data consumption of electrical energy for a year (5 December 2020–14 September 2021).

3.1.4. Electrical Power Losses in Distribution Lines

The unit of electric energy generated by power plants is different from the unit of electric energy provided to the customers. In a network, a certain percentage of the energy is lost. Distribution loss is the difference between the generated and distributed units.

3.2. Load Flow

The purpose of a power flow study is to investigate whether current, voltage, active power, and reactive power are flowing through a system at any given load. The load flow study will investigate the voltage and power factor across all buses as well as the current or power flow across all feeds [24]. To determine the steady-state operational characteristics of the power system for a specific load and generator’s real power and voltage settings, load flow calculations are utilized. Once we have these data, we can easily calculate the active and reactive power flow in each branch as well as the power losses. Power systems data are calculated using the Newton–Raphson approach in the load flow study. To start, a four-bus AC distribution system is used to test the suggested load flow computation approach. The first bus is a slack bus that represents the grade and has voltage values of “1 p.u.” and “0.22728 degrees” in terms of phase angle. Transmission lines are also connected to a step-down transformer that converts 33 kV to 11 kV and has a base value of 10 MVA. The university’s loads are supplied through a ring main electrical power distribution system by this transformer, which is connected to an AC substation. Renewable generation units are connected to a power frequency transformer that runs at 50 or 60 Hz and has a complex power of 10 MVA. This transformer is typically used to step up the output voltage, typically 11 kV, to the medium voltage level to achieve a compact and lightweight direct grid connection for solar PV (typically 33 kV). In a situation where the energy produced by a solar station is greater than the load that needs to be stored, the storage system is connected to the line so that it can sense changes in the load flow and utilize the extra energy. This stored energy is used at moments of peak load when the amount of energy generated is less than the amount consumed, as well as during times when there is no generation (at night), allowing the stored energy to be released and used to meet the demand.

4. Results and Discussion

The simulation results for the designed system will be displayed so that they can be compared and hence valuable information on the design and dimensioning of the PHES for the real plant may be obtained. The PV solar energy system’s generated data, as well as the electrical load, are used to provide output data of energy created and stored for the PHES. After modelling the system, the simulation was run to extract the following data, and the results were clear and suitable for analysis and comparison due to the huge number of samples.

4.1. PV Solar Power Results

Generated energy, like other electrical metrics, is a good predictor of an energy system’s efficiency, which is why it was the first to be plotted. Because solar energy is best seen in terms of time, a bar graph was created in which the solar energy generated by each piece of software throughout the 10 months of 2020–2021 (plotted on the x-axis) was compared. Values for both active power in kW and reactive power in kVAR were plotted separately, as shown in Figure 6, as well as for the PV system, so that any differences could be seen and investigated. Figure 6 shows how the station’s productivity varies depending on the season, solar radiation, and other factors. The station had the highest production value, at 4800 kWh, and a productivity of 9280.61 MWh.

4.2. Load Profile Results

Figure 7 represents the load at Mutah University for a year with no storage system. The change in university loads as a function of the seasons is shown in Figure 7. The largest loads and energy use were found to be in the winter season, due to the use of a lot of energy, especially for university heating, while the consumption was nearly half in the summer.

4.3. PHES Results

With the addition of the PHES unit and a complete system connection, it appears that the system has two operations: storage and pumping. Excess load energy due to energy productivity will be stored by operating the pumps and pumping the water into the high storage area, and this process will continue throughout the day until the loads exceed the energy productivity or the energy productivity values decrease, at which point the water will fall from the high storage area to the low storage area. The turbines, in turn, drive generators that provide electricity to the university, so the storage and pumping process is largely determined by the solar station’s productivity and the greatest load for that day, as shown in Figure 8. It appears that the PHES storage periods have negative sign energy, indicating that the system’s main energy is stored as potential energy. Positive sign energy indicates that the PHES pumps water from the stored area and produces electricity to feed the loads, indicating that the demand load and solar generation are matched. The PHES will only operate as a pump when there is a low demand load and as a generator when there is a peak load. As a result, the system remains steady during its daily activity as a storage and power generation system. It will be reliable as a true grid alternative, allowing it to cover the university’s needs without relying on the grid. The values, results, and improvements presented thus far have been evaluated every year, but as mentioned earlier, the calculation tool can be optimized for other months of the year. This would allow the entire plant to produce more in addition to having a better understanding of how each item operates and what effects different factors have. Samples were taken for 48 h to check the storage system’s behavior.

As shown in Figure 9, the load and productivity of the existing solar power plant were compared over time. Samples were taken for 48 h to check the storage system’s behavior. It was found that during the production period of the solar power plant, the university load was fed from PV-produced energy, and the excess energy was stored until the peak period, when the PV energy produced decreased because of the decrease in the rate of solar radiation; then the PHES system started generating energy to feed the load jointly with the PV solar energy production. When the plant stopped producing power (at night), the PHES system continued to feed the university’s loads alone until the next morning. In calculating the electrical maximum value that the design is based on, PHES max 4.3089 MW, it was found that this value is close to the value that was mathematically imposed, which is 5 MW; therefore, good agreement between the mathematical assumption and the model was obtained when a water storage system for the PV system was designed.

Figure 10 shows the power loss in the distribution network during the process of pumping and storing the required loads. These losses are caused by the distribution lines and their length, as opposed to the friction losses that occur in the pipes during water flow in the system; these are also caused by the distribution lines and their length.

Table 4 shows the average and maximum power losses of the proposed PHES system (in kW). As a result of the storage system’s operation on the network, total losses in the system were reduced, and the network became more stable and reliable.

5. Conclusions

Throughout this study, the effect of solar energy and PHES addition to Jordan’s electrical grid was investigated. Three main aspects of designing an energy storage system have been investigated: locating potential PHES installation sites at Jordan’s Mutah University; designing a PHES station; and simulating the actual power system module, which consists of solar generating units, loads, and PHES units. As a result of this research, we can conclude the following:

• Jordan has a significantly higher chance of installing a PHES because all necessary prerequisites have been met.

• The system would run efficiently and independently of the national electric network, reducing the university’s transit costs to the electrical distribution company.

• The system would render an annual energy production of 9230.89 MWh/year, an annual load yield of 4430 MWh/year, which would cover the Mutah University demand with an estimate saving of USD 287,607,993.

However, there are also some limitations and challenges of this approach, such as the high initial cost and maintenance of a pumped hydro storage system, the availability and suitability of the site for reservoirs and a solar PV system, and the environmental and social impacts of the construction and operation of the system.

Author Contributions

Methodology, M.Z. and M.A.-s.; Software, M.D.; Validation, Z.A.; Formal analysis, M.A.-s.; Investigation, S.A.-q.; Data curation, M.D.; Writing—original draft, M.D.; Writing—review & editing, Z.A.; Visualization, S.A.-q.; Supervision, S.A.-q. All authors have read and agreed to the published version of the manuscript.

Data Availability Statement

The data used to support the findings of this study are available from the corresponding author upon request.

Conflicts of Interest

The authors declare no conflict of interest.

Footnotes

Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Figures and Tables

Figure 1. Mutah University solar project.

Figure 2. Topography map for the proposed site.

Figure 3. Power capacity P (MW) of the main hydraulic turbines with head (m) [19].

Figure 4. Schematic of main components of the proposed configuration.

Figure 5. Solar PV system data obtained from Mutah University per day.

Figure 6. Solar power plant productivity.

Figure 7. Annual electricity load.

Figure 8. Annual PHES power.

Figure 9. PHES power storage process and production process over 48 h.

Figure 10. Active and reactive power losses over several months.

Table 1

The proposed PHES plant parameters.

Type of Machine	Reversible Pump–Turbine Unit (Francis)
Overall capacity	5 MW
Unit capacity	1 MW
Number of units	5 units
Rated head	85 m
Efficiency of generator	90%
Efficiency of pump	90%
Total Efficiency	81%
Rated discharge of turbine mode	1.33 (m3/s) for each unit
Rated discharge of pump mode	1.079 (m3/s) for each unit

Table 2

Characteristics of the PV modules.

Type	JAM72S01-340/SC
Peak power (PMAX)	340 W
Open circuit voltage (Voc)	46.32 V
Max. power voltage (Vmp)	37.87 V
Short circuit current (Isc)	9.60 A
Max power current (Imp)	8.98 A
Power selection	0~±5 W

Table 3

Characteristics of the inverter utilized in the Mutah University project.

PV input	565 Vdc–1000 Vdc 110 A/150 A max. rated current/Isc
Output	3P + PE, 380/400 Vac delta 352–440 Vac @400 Vac, 87.0 A Cos(Phi): 0.8…1…0.8 over/underexc. Max. output fault current: 49.8 over ms
Power	60 Kva@400 Vac, 45 °C/113 °F, Cos(Phi = 1)
Freq.	50/60 Hz (45–65)
Chassis	Outdoor IP65, protective class I Temp. −25 °C to 60 °C/−13 °F to 140 °F

Table 4

The average and maximum power losses of the proposed PHES system.

Average active losses (P)	3.6062 kW
Maximum active losses (P)	17.2833 kW
Average reactive losses (Q)	14.4996 kVAR
Maximum reactive losses (Q)	73.7099 kVAR

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